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Current Issue » November
From the River Valley Fliers RC Club, Plover-Wausau, Wisconsin
by Wayne Dempze
Finishing materials, and especially some of the
solvents they contain, react with one another. A
lacquer applied over an old coat of the same
material will partially dissolve the dry paint, so
lacquers rarely peel. Sometimes, when one kind of
paint is put over another, the whole finish may
dissolve and wrinkle up. We call this a
The table below shows what material can be applied
over others. We think you’ll find it easy to use.
For example, a builder might wish to use Aero Gloss
dope over a butyrate dope. Find Aero Gloss dope in
the top row which is labeled Over. Find the butyrate
dope in the left column labeled Under. The “N” in
the table shows the combination not to be
Maybe a model was originally sealed with dope over
the alkyd as the table shows. Perhaps a builder
wished to paint a model with one kind of paint and
trim it with another. The compatibility table shows
if the trim will react with the base color; however,
I don’t recommend this practice.
Here’s another example on how to use the chart.
Vinyl spackle is compatible over polyester resin.
Find vinyl spackle in the Over section and read down
to polyester resin. Now let’s reverse the two
materials. Vinyl spackle is not compatible when put
Under polyester resin.
Incidentally, always sand any color paint with 320
or 400 grit between coats. Sometimes paints need the
rough texture to bite into; not all finishes
partially dissolve earlier coats like lacquers do.
No doubt, some very skilled wood finishers may have
been able to use materials in a way we say is
incompatible. The table favors a conservative, safe
approach. Compatibility characteristics change
considerably with brands, weather, method of
application, and the reducers used. A finisher using
materials other than those listed had better plan to
test for compatibility on a scrap of wood prepared
in the same fashion as the model.
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© 2013 Academy of Model Aeronautics